Lubricating oil additives

ABSTRACT

THE N-HYDROXY HYDROCARBYL-SUBSTITUTED CYCLIC IMIDES, E.G., TETRAPROPENYLSUCCINIC HYDROXIMIDE, ARE MULTIFUNCTIONAL LUBRICATING OIL ADDITIVES WHICH SERVES TO INHIBIT RUST, REDUCE WEAR AND CONTROL FRICTION ON METALLIC SURFACES.

United States Patent Office 3,796,663 Patented Mar. 12, 1974 3,796,663 LUBRICATING OIL ADDITIVE Bruce W. Hotten, Orinda, Calif., assignor to Chevron v Research Company, San Francisco, Calif. No Drawing. Filed Sept. 29, 1971, Ser. No. 184,962

' Int. Cl. Cm 1/36 US. Cl. 252-515 A 4 Claims ABSTRACT OF THE DISCLOSURE The N-hydroxy hydrocarbyl-substituted cyclic imides, e.g., tetrapropenylsuccinic hydroximide, are multifunctional lubricating oil additives which serveto inhibit rust, reduce wear and control friction onmetallic surfaces.

BACKGROUND OF THE INVENTION Field of the invention Lubricating oil additives perform many functions: reduction of wear- 'and corrosion, controlof deposition of lacquer and sludge, oxidation inhibition, rust inhibition, control of friction, viscosity index improvement, pour point depression, extreme pressure lubrication, etc.

Few lubricants today are not compounded with such additives. Crankcase oils, turbine oils, industrial oils, gear oils, aviation and marine lubricants, and automatic transmission fluids all employ additives to achieve performance that cannot be obtained with Uncompounded oils. Uncompounded oils may fail to lubricate under high load necessitating the use of extreme pressure "additives to prevent excessive metal wear. Uncompounded oils may be displaced from contact with a clean metallic surface by drops of water necessitating the use of a rust inhibitor additive. Uncompounded oils when used as functional fluids may fail to control friction thereby "causing chatter and squawk, conditions which are alleviated by the use of frictional control additives.

Additives which are capable of imparting more than one property to an oil are termed multifunctional. Multifunctional additives are not 'alwa'y's'd'esirable. 'In some cases, separate additives for oxidation'inhibition, rust inhibition, etc., permit the most flexibility in lubricant formulation. But in the case of film-formers competing for the same surface, multifunctionality is highly desirable. For example, attempts to inhibit rust in extreme pressure 'gear' oils result in loss of EP strength because of additive competition at the gear tooth surface. I

We have found that hydroximides can be synthesized into structures that are highly soluble in oil, and function as rust inhibitors, antiwear agents, and frictional modifiers. Some potential applications are in industrial lubricants, crankcase oils, and transmission fluids,

Description ofthe prior art Cyclic hydroximides such as succinic, glutaric and phthalic are used as intermediates in peptide synthesis, US. Pat. 2,816,111. Hydroxamic acids, including dihydroxamic acids, have been proposed as lubricating oil additives, U.S. Pats. 2,279,560 and 2,279,973. US. Pat. 3,272,746 also describes certain substituted succinic acid derivatives as lubricating oil additives. -U.S.' Pats.'3,l21,-

Rust inhibition, wear reduction and frictional control on metallic surfaces is achieved at low concentrations of these hydroximides in lubricating oils. Past attempts to obtain several film-forming functions in one lubricant by combining individually effective additives have been incompletely successful, probably because of competition between the additives for the same surface. The new hydroximides offer a prototype structure that eliminates such competition by combining several functions in one additive.

In particular, the alkenylsuccinic hydroximides combine good rust inhibition, wear reduction and friction'al modification in one additive structure.

The hydrocarbyl substituent is an aliphatic or alicyclic hydrocarbyl of from 10 to 30 carbon atoms and preferably an alkyl or alkenyl group of from 10 to 25 carbon 'atoms.

The cyclic hydroximides of the present invention are recommended for use in industrial and automotive lubricants, transmission fluids and preservative oils requiring antirust, antiwear, and friction-modifying properties, especially when more than one of these properties is required in the same product.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The N-hydroxy hydrocarbyl-substituted cyclic imides of C -C dicarboxylic acids are of the general formula dependent to a large extent on the reaction by which the maleic acid or anhydride, in which case the double bond of 4 the maleic acid anhydride becomes saturated and there remains in the hydrocarbyl at least one olefinic double bond. If it is desired, the olefinic bonds may be saturated by hydrogenation.

Preferably an alpha-olefin, such as those obtained from cracking wax (cracked wax olefins) is reacted with maleic anhydride to form an alkenylsuccinic anhydride. This product may then be hydrogenated to form the alkylsuc cinic anhydride. The methods of reacting an olefin with maleic anhydride are well known in the art and do not requireexemplification here. Illustrative of various alphaolefins which may find use are l-decene, l-undecene, 1 dodecene, l-tridecene, l-tetradecene, l-pentadecene, 1- hexadecene, l-heptadecene, l-octadecene, l-nonadecene,

l-eicosene, l-heneicosene, etc.

When the addition reaction with maleic anhydride is utilized, or otherwise, it is often preferable to use as the olefinic hydrocarbon reactant a low molecular weight polymer or copolyrner of C -C olefins, i.e., an oligomer of C -C olefins. Such oligomers are, for example, tetrapropylene, triisobutylene, tetraisobutylene, etc.; these oligomers .are mono-olefins of a straightor branchedchain structure.

3 Method of preparation A preferred method of preparing the reaction product of this invention is the addition of the oligomer tetrapropylene or hexapropylene to maleic anhydride followed by reaction of the addition product with hydroxylamine generated in situ from hydroxylamine hydrochloride and triethylamine; other bases, such as calcium hydroxide, pyridine, or MgO may also be useful.

Because of the high viscosity of this system and the exothermicity of the reaction, a solvent such as toluene or a petroleum-based paint thinner is desirable. In a typical reaction, one heated equally molar portions of the anhydride and hydroxylamine hydrochloride with about percent excess triethylamine in toluene, amounting to about 20-80 percent of the total mixture. When the temperature reached about 90100 C., a strong exotherm occurred, rapidly raising the temperature to about 120- 30 C. The reaction was largely completed when the exotherm decreased, but was usually continued for an additional 1-3 hours at 100-140 C. The by-product, triethylammonium chloride, was washed out with Water, 'but filtration is also a possible method of separation. Azeotropic distillation with toluene can be used to remove the water of reaction. The hydroximide was identified by nitrogenanalysis, titration with base (the hydroximides titrate as weak acids), and by infrared spectra, which showed the loss of anhydride absorption and a gain of cyclic imide absorption.

The following examples illustrate the reaction conditions, reactants and products of the present invention, but are oifered for purposes of illustration rather than limitation.

Example 1 50 g. (approximately 0.1 mole) of cracked wax alkenylsuccinic anhydride, of C -C cracked wax olefin (equivalent weight 250), was mixed with 7.1 g. (approximately 0.1 mole) of hydroxylamine hydrochloride and 11 g. (approximately 0.11 mole) of triethylamine in 100 g. of toluene. The reaction proceeded at 110-115 C. for approximately 2 hours. The yield of product was 38 g. of waxy material, 2.3 percent nitrogen (2.7 percent calculated). IR analysis of the product showed the presence of imide bands at 1780 cm.- and 1720 cm.

Example 2 140 g. (approximately 0.4 mole) of cracked wax alkenylsuccinic anhydride,,of C -C cracked wax olefin (equivalent weight 175), was mixed with 29 g. (approximately 0.4 mole) of hydroxylamine hydrochloride and 43 g. (approximately 0.42 mole) of triethylamine in 60 g. of toluene. The reaction mixture was reacted at 90-120 C. for about 2 hours. The yield of product was 43 g. of waxy material, of 2.3 percent nitrogen (3.8 percent calculated). IR analysis of the product showed the presence of imide bands at 1780 and 1720 cmr Example 3 264 g. (approximately 1 mole) of tetrapropenylsuccinic anhydride was mixed with 71 g. (approximately 1 mole) of hydroxylamine hydrochloride and 111 g. (approximately 1.1 moles) of triethylamine in 150 g. of toluene. The

mixture Was reacted at 110 130 C. for about 3 hours. The yield of product was 228 g. of resinous material, of 4.28 percent nitrogen (4.99 calculated). IR analysis of the product showed the presence of imide bands at 178 0 and 1710 cm.

Example 4 Rust inhibition Results from three types of rust tests are given in Tables I and II.

TABLE I [Turbine Oil-Seawater Rust Test (ASTM D 665) and Demulsibility Test (ASTM D 1401)] Concen- Percent Emulsion Additive rus rust vol.

N one (base oil 0 Do. 0. 04 0 63 Tetrapropenylsuccinic hydroximide 0. 1 0 0 Hexapropenylsuccinic hydroximide 0. 1 25 1 Percent by weight in base oil.

2 Volume in milliliters.

5 Turbine oil base heavy, 470 SSU at 100 F. and 61 SSU at 210 F. 4 Cracked wax olefin of Example 1.

5 Cracked wax olefin of Example 2.

TABLE II [Humidity Cabinet Rust Test (a s'r l u D 1748) and Outdoor Exposure es Protection Protection time 1n time in I Concenhumidity outdoor Additive tratlon 1 cabinet 2 exposure 3 None (base oil 16 1 Myristic acid 1 70 Cracked wax alkeu uccinic hydroximide 5 1 180 3 Tetrapropenylsuccinic hydroximide 1 Hexapropenylsuccinic hydroximi 6 1 150 Calcium alkylbenzene sulfonate.. 1 1

1 Percent by weight in base oil.

2 Protection time, in hours, of sandblasted steel panel.

3 Protection time, in weeks, of sandblasted steel panel.

4 SSU, 100 F., neutral oil.

6 615-020 cracked wax olefin. Hydroximide solubilized in base oil with 7 percent 2-ethylhexanol.

Both tetrapropenyl and cracked was alkenylsuccinic hydroximides passed the Turbine Oil-Seawater Rust Test (ASTM D 665) and the Demulsibility Test (ASTM D 1401). Rust inhibition and compatibility with other additives were excellent.

In the Humidity Cabinet Rust Test (ASTM D-1748), both branched and linear carbon chain hyldroximides gave better rust inhibition than carboxylic acids such as myristic acid or tetrapropenylsuccinic acid.

The outdoor exposure test was conducted on sandblasted steel panels exposed to the Northern California rainy season. A linear carbon chain hydroximide inhibited rust better than a calcium sulfonate widely used as a lubricant additive.

Eflects on friction and wear Additives that reduce static friction are valuable in industrial lubricants because they also reduce the power requirements for starting machinery. A typical additive that performs ths function is myristic acid. We compared 5 hydroximides with myristic acid in the Godfrey Tribometer (ASLE Transactions, 7, 24-31 (1964)). In this device a SAE 52100 steel needle from a needle bearing was pressed vertically againnst the side of a rotating A81 4615 steel Timken roller bearing cup; a strain gauge measured the friction between them. Results in Table III show that both myristic acid and a cracked wax alkenylsuccinic hydroximide reduced static friction by 47 percent.

TABLE III [Friction and wear tests] Coeflicient of friction 1 Needle wear 3 A static A volume Additive Kinetic Static percent Volume percent None (base oil 0. 16 0. l9 1. 6 Myristie acid 0.10 0.10 47 1. 4 12 Tricresyl phos phate 9. 12 0. 13 32 0. 47 70 Cracked wax alkenylsuccinie hydroximide 0. 11 0. 10 -47 0. 50 -69 Tetrapropenylsuccinichydroximide 0. l3 0. 16 16 0. 99 38 Hexapropenylsucoinic hydroximide 0. 13 0. 22 +17 0. 50 ---69 l Additives at 1% by weight in base oil.

2 Godfrey Tribometer; A static measured relative to base oil; load of 1 kg.; speed of 0.4 fpm; time, 2 hours.

B Godfrey 'lribometer; A volume measured relative to base oil; volume in units of 10- mmfi.

Base oil; 130 SSU, 100 F., neutral oil.

5 015-020 cracked wax olefin. Hydroximide soiubilized in base oil with 7% i 2-ethylhexanol.

Antiwear agents are valuable in lubricants for applications in which full hydrodynamic lubrication does not always exists A typical steel/steel antiwear agent is tricresyl phosphate. It reduced needle tip wear in the Godfrey Tribometer test by 70 percent. The cracked wax and hexapropenylsuccinic hydroximides reduced it by 69 percent and the tetrapropenylsuccinic hydroximides reduced wear by 38 percent. Thus, the hydroximide can reduce both friction and wear as well as each specialized additive, besides inhibiting rust. The specialized additives mixed together in a lubricant for these separate functions would compete with each other for the metal surface, consequently some properties would suffer.

Another frictional property of interest is the relative static and kinetic coefficients of friction between the fibrous and steel members of clutch plates in an automatic transmission. General Motors requires automatic transmission fluids (ATF) that produce lower static than kinetic friction. Ford requires the opposite relationship, 1.e., higher static than kinetic coetiicients of friction. It has been found that cracked wax alkenylsuccinic hydroximide meets the General Motors requirement and the tetrapropenylsuccinic hydroxide meets the Ford requirement in simple oil solutions. That is, the coeflicient of friction decreases with increasing speed for the tetrapropenyl-derivative solution and shows the opposite be havior for the cracked wax alkenyl derivative solution.

The multifunctional action of the N-hydroxy hydrocarbyl-substituted cyclic imides of C -C dicarboxylic acid (e.g., hydrocarbyl-substituted succinic hydroximides) oifers a potential solution to the problem of combining several film-forming properties in one lubricant while avoiding competition among separate additives for the same surface. These hydroximides are useful lubricating oil additives in industrial and automotive lubricants,

transmission fluids and preservative oils requiring antirust, antiwear, and friction-modifying properties.

The compositions of this invention may be used with a wide variety of lubricating media, including oils of lubricating: viscosity, as well as greases. Various base oils which find use include oils such as petroleum lubricating oil; naphthenic base, paraffin base, and mixed based; synthetic oils; alkylene polymers and alkylene oxide polymers; esters of organic and inorganic acids; acryl hydrocarbons,and ethers; organic silicone compounds; etc. The base oils can be used individually or in combination, wherever miscible or wherever made so by the use of mutual solvents.

The additives of the present invention will be present in lubricating oils and greases in concentrations of from 0.01 to about 5 percent by weight, and preferably 0.05 to about 3 percent by weight. In addition, these lubricating compositions may also contain other lubricating oil and grease additives such as oiliness agents, extreme-pressure agents, rust inhibitors, oxidation inhibitors, corrosion inhibitors, viscosity index improving agents, dyes, detergents, dispersants, etc. The total amount of these additives will usually range from about 0.1 to 20 percent by weight, and more usually from about 0.5 to 10 percent by weight. The individual additives may vary in amounts from about 0.01 to 10 weight percent of the total composition.

As will be evident to those skilled in the art, various modifications of this invention can be made or followed in the light of the foregoing discussion and disclosure- R-CH NOH

wherein a and b are integers, a is equal to 0, or 1, b is equal to, or 1, a plus b is equal to 1, and R is alkyl or alkenyl group of from 10 to 30 carbon atoms.

3. A lubricating oil composition according to claim 2 wherein R is selected from the group consisting of tetrapropenyl and hexapropenyl.

4. A lubricating oil composition according to claim 2 whereinR is derived from olefin of average molecular weight in the range from to 500.

References Cited UNITED STATES PATENTS 2,279,560 4/1942 Dietrich 252-51.5 A 2,279,973 4/1942 Dietrich 25251.5 A 3,407,204 10/1968 Shay et al. 25251.5 A 3,367,959 2/1968 Fetscher et al. 25251.5 A

WERTEN F. W. BELLAMY, Primary Examiner US. Cl. X.R.

260326.5J 326.5 F, 326.5 FM

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,796,663 Dated March 12, p7 4 Ihventor(s) BRUCE W. HOTTEN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4, line 25 "Concen-rust" should read --Concentration-.

Col. '4, line 55, "cracked was" should read --cracked wax--.

Col. line 6 l," "hyldroximides" should read -hydroximides--.

Col. 5, line l7, "9.12" should read --O.l2--.

Col. 5, line 53, "hydroxide" should read --hydroximide--.

Col. '6, line 45, "equal to, or 1" should read --equal to 0, or 1- Signed and sealed this 16th day of July 1974.

(SEAL) Attest:

MCCOY M. GIBSON, "JR; 0. MARSHALL DANN Attesting Officer Commissioner of Patents 

